This class is a stream filter which reads in string encoded samples and creates
TokenSamples out of them. The input string sample is tokenized if a
whitespace or the special separator chars occur.

Sample:
"token1 token2 token3<SPLIT>token4"
The tokens token1 and token2 are separated by a whitespace, token3 and token3
are separated by the special character sequence, in this case the default
split sequence.